In recent years, research and development on light emitting diodes (LEDs) of blue and green made of GaN-based semiconductor are being promoted. In an LED of an FU (Face Up) type, an oxide transparent conductor such as ITO (Indium Tin Oxide) is generally used as a transparent conductor on a p-type GaN layer.
To make the drive voltage of the LED low, it is necessary to decrease contact resistance between ITO and the p-type GaN layer. However, the Schottky barrier height between ITO and the p-type GaN layer is high as 3.2 eV, and it is difficult to decrease the contact resistance.
There is proposed a technique of reducing the Schottky barrier height by using ITON (Indium Tin Oxynitride) obtained by adding nitrogen thereto and forming ohmic contact. A technique of stacking an oxide transparent conductor and an oxynitride transparent conductor on the p-type GaN layer is also proposed.